1. Field of the Invention
The present invention relates to a method of recording and reproducing data, and more particularly, to a method of recording and reproducing contents, recording and reproduction of which are restricted within a predetermined domain, in response to a write/read command input from a host with a domain management system.
2. Discussion of Related Art
Various types of multimedia reproducing apparatuses, such as a video tape recorder, a personal computer, an audio player, a television, and a personal digital assistant (PDA), have been used in households or offices. In general, contents such as video or music data reproduced by such apparatuses is copyrighted, and thus, its use is limited to authorized users. In general, the use of such contents is managed physically in units of individual residences including a household or an office, and a user who occupies an individual residence is charged a fee for using the contents.
In general, management of the use of contents in units of individual residences is controlled by a domain management system. The domain management system includes a home server that temporarily stores external contents, newly sets a right for accessing within a current domain, and manages rights for devices accessing the current domain. The domain management system also includes various types of reproducing apparatuses that are connected to the home server, given contents and a right to access the contents, and reproduce the contents.
The domain management system is referred to as application software installed in the home server and the reproducing apparatuses. The home server that provides rights to the contents to a reproducing apparatus and manages use of the contents, or application software installed in the home server that provides these features is referred to as a master. The reproducing apparatus or application software installed therein is referred to as a slave.
There are various types of domain management systems such as IBM's xCP and Thomson's SmartRight. These domain management systems have the following common characteristics. First, contents is provided by a master, and the master generates a domain key available only in a domain to which the master belongs and provides the domain key to its slave. Second, the master determines whether use of the contents provided in the domain is limited to authorized users, encrypts contents, use of which is limited, and sends the result of encrypting to its slave. Third, a content key for encrypting the contents is encrypted using the domain key and the result of encrypting is sent to the slave. Fourth, the master replaces a previous domain key with a new domain key, when a slave joins or leaves the domain or an illegally copied device is detected, and thus the right for the contents needs to be changed.
The slave temporarily stores the contents provided by the master in its memory and reproduces it later if necessary. However, the contents is preferably stored in an external storage medium, e.g., an optical disc, rather than in the memory of the slave, and is reproduced from the external storage medium if necessary.
However, when the existing domain key is changed, a conventional recording/reproducing apparatus subject to a slave cannot store contents input via the domain management system in an external storage medium and reproduce it later. In detail, the contents is encrypted using the content key, the content key is encrypted by the domain key; thus when the domain key is changed and provided to the slave when a new slave or an illegally copied slave accesses the domain or a previous slave is disconnected from the domain, the domain key used to encrypt the contents is no longer useful.
Since the external storage medium is not always connected to the slave, it is impossible to update information regarding a new domain key in the external storage medium in real time. Also, once the new domain key is provided to the slave, information regarding a previous domain key used when storing the contents in the external storage medium is deleted from the slave. In this case, the conventional recording/reproducing apparatus is not capable of reproducing the contents.